Mechanical, tribological and electrochemical behavior of Zr-based ceramic thin films for dental implants

Abstract

To determine the possibility of using new thin films architectures as biocompatible materials, an experimental and computational study was performed to evaluate the mechanical, tribological, and corrosion properties in simulated physiological media (saliva and blood plasma) of Zr, ZrN, and ZrN/Zr coatings, deposited by PVD magnetron sputtering. The crystalline structure and chemical composition were well correlated with high resistance to plastic deformation, wear, and corrosion, making these materials excellent candidates for functionalizing and protecting dental prostheses. The predominant wear mechanism under consideration was abrasion, which was reduced when using ceramic ZrN coating as a base for the superficial Zr thin film. When exposed to simulated body fluids, these materials exhibited high corrosion resistance, which was demonstrated by potentiodynamic measurements. These results are consistent with those predicted by Density Functional Theory computational models, which showed that electron transfer associated with the wear mechanism is kinetically impeded, as a consequence of the large energy barriers for this process associated with the adsorption of the molecular species on the ZrN surface. Additionally, calculated adsorption energies indicated that urea (from the simulated saliva solution) interacts strongly with the surface. This interaction was associated to the formation of passivating protective layers, which is a key mechanism to protect against corrosion, acting in synergy with the kinetic barriers.